Cancer is a major cause of morbidity in the United States. Cancers share the characteristic of disordered control over normal cell division, growth and differentiation. Their initial clinical manifestations are extremely heterogeneous, with over 70 types of cancer arising in virtually every organ and tissue of the body. Moreover, some of those similarly classified cancer types may represent multiple different molecular diseases. Unfortunately, some cancers may be virtually asymptomatic until late in the disease course, when treatment is more difficult and prognosis grim.
Treatment for cancer typically includes surgery, chemotherapy, immunotherapy and/or radiation therapy. Although nearly 50 percent of cancer patients can be effectively treated using these methods, the current therapies all induce serious side effects, which diminish quality of life. The identification of novel therapeutic targets and diagnostic markers will be important for improving the diagnosis, prognosis, and treatment of cancer patients.
Antigens suitable for immunotherapeutic strategies should be highly expressed in cancer tissues, preferably accessible from the vasculature and at the cell surface, and ideally not expressed in normal adult tissues. Expression in tissues that are dispensable for life, however, may be tolerated, e.g., reproductive organs, especially those absent in one sex. Therefore, provided herein is a protein that can be used as a biomarker and methods that can be used in diagnosis, prognosis and therapeutic monitoring of cancer and cancer patients, as well as therapeutic treatment of cancer patients.
Research in solid tumors has focused primarily on identifying targets and biomarkers present in the in the cancer epithelia. Very few strategies have focused on identifying genes up-regulated in the stroma that surrounds cancer tumors. Studies have shown that stromal-derived growth factors, stroma-produced extracellular matrix and/or the interaction of cancer epithelia with specific stromal cell antigens are important for tumorigenesis (Clamps et al. Proc. Natl. Acad. Sci USA 87: 75-79, 1990, Olumi et al., Cancer Res., 59: 5002-5011, 1999; Elenbaas et al., Genes Dev., 15: 50-65, 2001; Tuxhom et al., Cancer Res. 62:3298-3307, 2002). Cancer therapy, therefore, includes targeted therapies towards the tumor-associated stroma and their factors. Effective therapy targets the activated stroma during the proliferation stage. This results in preventing the stroma from producing a pro-tumor microenvironment. The loss of this vital nutrient and growth factor supply line to the tumor cells ultimately results in tumor cell death. One such target for targeting the stroma is antibodies to the full length LFL2 protein and fragments thereof. LFL2 (also referred to in the literature as Lib and LRRC15) is a member of the leucine-rich repeat superfamily of proteins. LFL2 is a type I transmembrane protein with an extracellular domain that contains fifteen leucine-rich repeats. The full-length amino acid sequence of LFL2 is depicted in SEQ ID NO:1. The LFL2 gene is identical to LRRC15 (“leucine rich repeat containing 15”) (Satoh, et al., Biochem. Biophys. Res. Commun., 2002; 290:756-62; Reynolds et al., Genes Dev., 2003; 17:2094-107; WO 01/81363, see, sequence id numbers 4 (DNA) and 43 (protein); and WO 02/081518, see, sequence id numbers 75 (DNA) and 76 (protein)) whose nucleic acid and amino acid sequences can be identified by Genbank Accession Nos. NM—130830.2 and NP—570843.1 respectively. The Unigene cluster identification number for LFL2/LRRC15 is Hs.288467 and the LocusLink ID is 131578. Satoh, et al. also describes RT-PCR and Northern blot data showing that LFL2 is strongly expressed in placental cells. High placental expression of LFL2 based on RT-PCR data was also disclosed in WO 01/81363 along with the general suggestion of cancer as one of several possible disease indications.
WO 02/081518 discloses RT-PCR expression data associating LFL2 with breast cancer, melanoma and brain cancer. WO 02/081518 also states that antibodies to these proteins can be generated for use in therapeutic and diagnostic methods.
WO 03/024392 discloses RT-PCR and DNA microarray results and concludes that LFL2 is upregulated in breast, uterine, colon, kidney, bladder, bone, ovarian and pancreatic tumor tissues. WO 03/024392 also reports GeneExpress® data and concludes that LFL2 is upregulated in stroma associated with bone, breast, colon, rectum, lung, ovarian, pancreas, soft tissue and bladder tumors. WO 03/024392 also reports in situ hybridization data and concludes that LFL2 expression occurs in a minority of sarcomas including synovial sarcoma, angiosarcoma, fibrosarcoma, gliosarcoma and malignant fibrohistiocytoma.
Furthermore, Reynolds et al. (Genes & Development 17: 2094-2107 (2003)) disclose LFL2 and describe RT-PCR, Northern blot and in situ hybridization data. Reynolds et al. observe that LFL2 is restricted to the cytotrophoblast layer, and, consequently, conclude that LFL2 may contribute to the invasiveness of breast cancer cells.
Expression of the rat ortholog of LFL2 is induced in rat C6 astrocytoma cells by pro-inflammatory cytokines (Satoh, et al., Biochem. Biophys. Res. Commun., 2002; 290:756-62). LFL2 expression is also induced by the presence of EWS-WT1(+KTS) (Reynolds et al., Genes Dev., 2003; 17:2094-107), a chimeric oncogene that is expressed in desmoplastic small round cell tumors (DSRCT). DSRCTs are soft tissue tumors that occur in primarily male children and young male adults. In this published report, expression of LFL2 in cancer cell lines was associated with breast cancer cell migration in vitro, suggesting a function of LFL2 in the aggressiveness and invasiveness of cancer.
Solid tumors often exhibit high interstitial fluid pressure (IFP), which causes poor uptake of anticancer drugs. While there are several mechanisms that regulate IFP in tumors, stroma-derived connective tissue control IFP by exerting a tension on the extracellular matrix/integrin. Agents known to reduce the tumor IFP have been shown to enhance the anti-tumor activity of chemotherapeutic agents (Griffon-Etienne et al., Cancer Res., 1999, 59:3776-82; Salnikov et al., FASEB J., 2003, 17:1756-8).
In spite of considerable research into for the molecular level mechanisms of cancer in general, cancer remains difficult to diagnose and treat effectively. Accordingly, there is a need in the art for improved methods for detecting and treating cancers. The present invention fulfills these needs and further provides other related advantages.